Automatic train-control apparatus



Aug. 14, 1928. 1,680,665

P. J. CLIFFORD AUTOMATIC TRAIN CONTROL APPARATUS Original Filed Feb. 20, 1923 sis/VAL TRAIVJMISS/ON 411v:

STANDARD 4.0. TRANSFORMER F WWW mulummuzl I I l l l l I I t I I I 1 l I I I l I I o I l l I g3 TRAFFIC l I l l I I/C' A-C. TRACK RELAY Z i LIGHT LIA/CS EX/JT/NG SIG/VALL/IVG CIRCUITS.

HEAVY LINES CLIFFORD IMPDSED C/RCU/TJ.

70 SECMM RELAX? E751, CONTROLLING BRA/f5 APPLY/1Y6 MIA/V6 AND SIGN/1L6.

Inaentor:

Patrick J czi rd,

Patented Aug. 14, 1928.

UNITED STATES PATENT OFFICE.

PATRICK J. CLIFFORD, OF FALLS, PENIVSYLII'ANIA, ASSIGNOR, BY MESNE ASSIGN- MENTS, TO TRAIN CONTROL CORPORATION OF AMERICA, A CORPORATION OF DELAWARE.

AUTOMATIC TRAIN -CON TROL APPARATUS.

Application filed February 20, 1923, Serial No. 620,287. Renewed November 12, 1927.

In applications for Letters Patent of the United States filed by me, April 17,1922, No. 553,4;29, and Jan. 5, 1923, No. 610,879, a train stop system is described in which a primary relay on the vehicle is arranged in a c0nductor receiving current from the traflic rail system, due to the drop in potential between the points of contact of said conductor with the rail system. The present invention is designed to carry out said system of train control in connection with an alternating current installation.

In the accompanying drawings.

J Figure 1 is a diagram of the track wiring and associated apparatus.

Fig. 2 is a diagram. of the primary relay on the vehicle and certain parts and wiring associated therewith.

The present system may be used to impose alternating current onthe traflic rails in addition to that imposed for signaling purposes, but as the present system involves the use of signals on the engine, it may be employed Where no roadside signalling system exists if so desired.

In the present system a transmission line and transformers replace the storage batteries of the imposed track circuit'of the Clifford system. These two elements already exist where there is an A. C. signalling sys tem present. The'Clifi'ord circuits may be operated from the same source as the signalling track circuit without interference between them.

The control of the imposed current is as in the said Clifford applications througha front contact of the relay in the next block ahead of the block occupied by'the vehicle, and through a back contact of the relay in its own block. When a train enters the block, its track relay T R is shunted, and contact 2 closes. Then, if there is no train in the block ahead, and the relay of that block is picked up, and contact 9 closed, a path of current is provided from transformer coil 1 through line wire, contact 2, to the middle of resistance R at 3. Here the current divides equally into the two rails and proceeds through paths 46, and 57 to R, where it reunites at 8, passes through contact 9, and back to transformer at 10.

Interference with the signalling track cuits at present in use is avoided by means of the resistances R and R which are of a high enough value to have a negligible shunting effect on the signallig track circuit. The imposed circuit voltage may be, and preferably is, from 5 to 20 times that of the signalling track circuit voltage. Hence the resistance R and B have a negligible effect upon the imposed circuits. In Figure-1 the track circuit shown is an A. C. track circuit as applied wherethere is electric traction. Any other form of track circuit employing insulated joints equally well may be used, for obviously resistances R and R are sufficient protection against shunting for the low voltage that exists in any signalling track circuit at present in use.

Figure 2 represents the circuits of the pri mary relay onthe engine. Due to the small amount of energy received through the wheels. the relay on the engine is additionally controlled bya source of current on the vehicle. The invention, however, is not limited in all'respects to the use of this additionally excited relay.

Two relay units connected in multiple as shown, are employed. S and S are the sec ondary coils of these units, supplying the most of the torque, and energized from a suitable source on the engine, as described later. P and P are the primary coils, energized through the wheels by any of the various connections already described heretofore in the said Clifiordapplications. Both primary and secondary are energized by A. C. of approximately the same frequency, and contact K and K are made when the primary and second circuits are ,not in phase. "If either circuit, primary or secondary, is unenergized, contacts K and K are broken.

The reason for the duplication-of relays now will be clear. They are dependent for their motion to close their respective contacts when the currents in the primary and secondarycircuits are out of phase. To obviate the difficulties of synchronizing primaries and secondaries, since they are derived from entire ly independent sources, the two secondaries S and S are suitably connected by means of capacitances andreactances C and G and L and L so that they are in quadrature with each other; This insures that the pria maries P and P are energized, one of the two contacts K and K will he closed.

The local sources of A. C. for the seeondaries may he obtained from any suitable source. A small turbo-generator operated from the steam mains on the engine, governor controlled to give'the proper frequency, may be used. Or, as shown in the drawing, a small synchronous converter, inverted, operated by the engine storage battery, may be used. This perhaps represents the ideal form, since it is, when once connected, readily adjustable tO-PIOPEI' speed. A mechanical rectifier of suitable construction may also be used.

There is no necessity that the frequencies of the primary and secondary be the same. but better operation prevails. Contacts K and K may be placed in the brake solenoid controlling circuits as desired.

It will be understood that the vehicle will have thereon means for causing the stopping of the train when the primary relay is deenergized, or signal means for indicating restrictive conditions ahead when said primary relay is deenergized, or both stopping and signalling means may be employed to operate conjointly and controlled by the primary relay, and whether either one or both are used an indication will result of the conditions ahead, either by the operation or non-operation of the stopping means or the existence or non-existence of the signals, the system like that of Clifford being one of continuous control. The wires O and X will connect up with the various appliances necessary to carry out the Clifi'ord system, all operated by direct current, such as the various relays and the brake controlling solenoid of that system. I

It will be understood that the description and diagrams are illustrative of the invention and are not to be regarded as restrictive upon the scope thereof which is defined by the accompanying claims.

The primary relay shown herein is made the subject of an application filed by Andrew Langdon Feb. 20, 1923, Serial No. 620,283.

I claim:

1. In combination in train control apparatus means for imposing alternating current upon the traific rails including a track relay for each block which is (lo-energized when said block is occupied, an alternating current circuit which is closed by the dropping of said relay and by the picked up relay oi the unoccupied block in advance, said circuit including a resistance extending across between the rails at each end of the block and with which the ends of the circuit conductor connect through the hack contact of the relay of the occupied block and the front contact of the unoccupied block in advance, said conductor deriving its current through a transformer from the transmission line, primary relay means on. the engine a conductor receiving curent from the trallic rail system due to the drop in potential between its points of contact therewith, and train control means on the vehicle controlled by said relay for maintaining or indicating a proceed condition while said primary relay is energized, and for causing a stop or indicating restrictive condition ahead when said primary relay is de-energized.

2. In combination in train control appa ratus. means for imposing alternating current upon the traffic rails, including a track relay for each block which is (lo-energized when said block is occupied, an alternating current circuit which is closed by the dropping of said relay and by the picked up relay ot' the unoccupied hlockin advance. said circuit including a resistance extend ing across: between the rails at each end of the block and with which the ends of the circuit conductor connect through the hack contact of the relay of the occupied block and the front contact of the unoccupied block in advance, said conductor deriving its current through a transformer from the transmission line, primary relay means on the engine in a conductor receiving current from the traflic rail system due to the drop in potential between its points of contact therewith. and train control means on the vehicle controlled by said relay for maintaining or indicating :1 proceed condition while said primary relay is energized. and for causing a stop or indi eating restrictive conditions ahead when said primary relay is deenergized, said cross rcsistances being of sufiiciently high resistance as to prevent interference with the track signalling circuit. said t'ansmission line heinn that of the signal system. substantially as described.

In testimony whereof I ailix my signature.

PATRICK J. CLIFFORD.

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